Skin cancer generally develops in epidermis which is outermost layer of the skin. Firstly cancer occurs when normal cells undergo transformation during which they grow, multiply and results in the formation of mass called tumor. Tumor may be malignant which spread across the body or benign which do not spread. Normally tumors are cancerous only if they are malignant.

Skin cancer is the most common form than any of human cancers. It is seen in both men and women of younger population (20-40 age). It is seen more in United States, U.K, and Australia.

Types:

There are many types of skin cancer. The most common types are:

• Basal carcinoma - this is the most common form and accounts for 75 % of skin cancer. It is usually found on face, neck and hands. It rarely spreads to other parts of the body. It can be treated easily.

• Squamous Cell Carcinoma - these are usually found in places like ear, face, mouth and areas exposed to sun. These can spread quickly to other parts of the body. It can be treated easily if detected early.

• Melanoma - it is the most dangerous type of skin cancer and it spreads quickly to any part of the body through lymph nodes or blood.

Other various types which are less common are:

• Merkel cell carcinoma - it is of rare type, in this nodule are seen in red, pink, blue color beneath the skin and usually found on places where body is exposed to sun.

• Sebaceous gland carcinoma - it is uncommon and originates from oil glands of skin. It appears as painless nodules seen on eyelid.

• Kaposi sarcoma - this is present in skin blood vessels. It is mainly seen in people with weakened immune system like HIV/AIDS.

Skin cancer generally starts as precancerous lesions and slowly changes to patches of red or brown, scaly, rough skin called Actinic Keratosis and develops into Squamous cell carcinoma, and then changes in moles leads to melanoma.